• Authors:
    • Johnson-Maynard, J. L.
    • Lentz, R. D.
    • Brown, B.
    • Lehrsch, G. A.
    • Leytem, A. B.
  • Source: Agronomy Journal
  • Volume: 107
  • Issue: 1
  • Year: 2015
  • Summary: To grow sugarbeet ( Beta vulgaris L.) profitably, producers must effectively manage added N, whether from inorganic or organic sources. Our objective was to determine if equivalent sugarbeet root and sucrose yields could be achieved when substituting dairy cattle ( Bos spp.) manure, either composted or stockpiled, for conventional N (urea) fertilizer. First-year treatments at Site A (Parma, ID) included a control (no N), urea (202 kg N ha -1), compost (218 and 435 kg estimated available N ha -1), and manure (140 and 280 kg available N ha -1). Site B (Kimberly, ID) treatments were a control, urea (82 kg N ha -1), compost (81 and 183 kg available N ha -1), and manure (173 and 340 kg available N ha -1). Compost and manure were incorporated into two silt loams, a Greenleaf (fine-silty, mixed superactive mesic Xeric Calciargid) at Parma in fall 2002 and 2003 and a Portneuf (coarse-silty, mixed superactive, mesic Durinodic Xeric Haplocalcid) at Kimberly in fall 2002. Sugarbeet was planted the following spring. Sucrose yield averaged across years and organic N rates at Site A was 12.24 Mg ha -1 for urea, 11.88 Mg ha -1 for compost, and 11.20 Mg ha -1 for manure, all statistically equivalent. Doubling the organic N rates at Site A increased the yield of roots up to 26% and sucrose up to 21%. Applying organic amendments in place of urea affected neither root nor sucrose yields but, at one location, decreased sugarbeet quality, though without hindering sucrose recovery. Sugarbeet producers can use compost or manure to satisfy crop N needs without sacrificing sucrose yield.
  • Authors:
    • Keeton, W. S.
    • Mika, A. M.
  • Source: Research Article
  • Volume: 7
  • Issue: 3
  • Year: 2015
  • Summary: The long-term greenhouse gas emissions implications of wood biomass ('bioenergy') harvests are highly uncertain yet of great significance for climate change mitigation and renewable energy policies. Particularly uncertain are the net carbon (C) effects of multiple harvests staggered spatially and temporally across landscapes where bioenergy is only one of many products. We used field data to formulate bioenergy harvest scenarios, applied them to 362 sites from the Forest Inventory and Analysis database, and projected growth and harvests over 160 years using the Forest Vegetation Simulator. We compared the net cumulative C fluxes, relative to a non-bioenergy baseline, between scenarios when various proportions of the landscape are harvested for bioenergy: 0% (non-bioenergy); 25% (BIO25); 50% (BIO50); or 100% (BIO100), with three levels of intensification. We accounted for C stored in aboveground forest pools and wood products, direct and indirect emissions from wood products and bioenergy, and avoided direct and indirect emissions from fossil fuels. At the end of the simulation period, although 82% of stands were projected to maintain net positive C benefit, net flux remained negative (i.e., net emissions) compared to non-bioenergy harvests for the entire 160-year simulation period. BIO25, BIO50, and BIO100 scenarios resulted in average annual emissions of 2.47, 5.02, and 9.83 Mg C ha -1, respectively. Using bioenergy for heating decreased the emissions relative to electricity generation as did removing additional slash from thinnings between regeneration harvests. However, all bioenergy scenarios resulted in increased net emissions compared to the non-bioenergy harvests. Stands with high initial aboveground live biomass may have higher net emissions from bioenergy harvest. Silvicultural practices such as increasing rotation length and structural retention may result in lower C fluxes from bioenergy harvests. Finally, since passive management resulted in the greatest net C storage, we recommend designation of unharvested reserves to offset emissions from harvested stands.
  • Authors:
    • Southard, R. J.
    • Horwath, W. R.
    • Shrestha, A.
    • Mitchell, J. P.
    • Madden, N.
    • Veenstra, J.
    • Munk, D. S.
  • Source: Article
  • Volume: 107
  • Issue: 2
  • Year: 2015
  • Summary: Rising costs and air quality regulations have created interest in California's San Joaquin Valley (SJV) in production systems that reduce tillage operations and soil disturbance. From 1999 to 2009, we evaluated conventional (CT) and reduced tillage (RT) systems for a cotton ( Gossypium hirsutum L.)/tomato ( Solanum lycopersicon Mill.) rotation with (CC) and without (NO) cover crops in a Panoche clay loam soil (fine-loamy, mixed, superactive, thermic Typic Haplocambid) in Five Points, CA, in terms of yield, soil C, and the NRCS soil conditioning index (SCI). The RT reduced tractor operations by 50% for tomato and 40% for cotton. Cover cropping produced 38.7 t ha -1 of biomass. Tomato yields were 9.5% higher in RT vs. CT systems and 5.7% higher in NO vs. CC systems. The CT cotton yields were 10.0% higher than RT yields and 4.8% higher in NO systems, but yield patterns were not consistent from 2005 to 2009. Soil C content was uniform (0-30-cm depth) in 1999 (19.72 t ha -1) and increased in all systems in 2007 (t ha -1): RTCC 29.11, CTCC 26.36, RTNO, 24.09, and CTNO 22.65. Soil C content of RT and CT systems did not differ, but was greater in CC than in NO systems. In the 0- to 15-cm depth, RT increased soil C, indicating stratification, and also increased C in the occluded light and mineral fractions. The SCI was positive for RT treatments, predicting a soil C increase, and negative for CT systems, predicting a soil C decline, but measured soil C content increased in all systems. Results show that RT maintains or increases yields relative to CT, and CC stores more soil C than NO.
  • Authors:
    • Arbuckle, J. G.
    • Hobbs, J.
    • Morton, L. W.
    • Loy, A.
  • Source: Web Of Knowledge
  • Volume: 44
  • Issue: 3
  • Year: 2015
  • Summary: Persistent above average precipitation and runoff and associated increased sediment transfers from cultivated ecosystems to rivers and oceans are due to changes in climate and human action. The US Upper Midwest has experienced a 37% increase in precipitation (1958-2012), leading to increased crop damage from excess water and off-farm loss of soil and nutrients. Farmer adaptive management responses to changing weather patterns have potential to reduce crop losses and address degrading soil and water resources. This research used farmer survey ( n=4778) and climate data (1971-2011) to model influences of geophysical context, past weather, on-farm flood and saturated soils experiences, and risk and vulnerability perceptions on management practices. Seasonal precipitation varied across six Upper Midwest subregions and was significantly associated with variations in management. Increased warm-season precipitation (2007-2011) relative to the past 40 yr was positively associated with no-till, drainage, and increased planting on highly erodible land (HEL). Experience with saturated soils was significantly associated with increased use of drainage and less use of no-till, cover crops, and planting on HEL. Farmers in counties with a higher percentage of soils considered marginal for row crops were more likely to use no-till, cover crops, and plant on HEL. Respondents who sell corn through multiple markets were more likely to have planted cover crops and planted on HEL in 2011. This suggests that regional climate conditions may not well represent individual farmers' actual and perceived experiences with changing climate conditions. Accurate climate information downscaled to localized conditions has potential to influence specific adaptation strategies.
  • Authors:
    • Kovacs, P.
    • Omonode, R. A.
    • Vyn, T. J.
  • Source: Article
  • Volume: 107
  • Issue: 2
  • Year: 2015
  • Summary: Precision-guided technologies enable corn ( Zea mays L.) growers to apply pre-plant anhydrous ammonia (NH 3) parallel to intended corn rows even when full-width tillage follows NH 3 application. Close, but crop-safe, proximity of NH 3 to corn rows may potentially increase N use efficiency and lower N requirements and nitrous oxide (N 2O) emissions. Experiments in 2011 and 2012 on silty clay loam Mollisol near West Lafayette, IN, assessed area- and yield-scaled N 2O emissions when spring pre-plant NH 3 was applied at recommended (202 kg N ha -1) and reduced rate (145 kg N ha -1), in no-till (NT) and conventional tillage (CT) systems following NT soybean [ Glycine max (L.) Merr.]. Each 12-cm deep NH 3 band was positioned 15 cm from, and parallel to, intended corn rows using precision guidance. Nitrification of NH 3 in application bands was 31% faster under CT than NT. Area- and grain yield-scaled N 2O emissions were N rate dependent in both growing seasons. On average, CT+202 kg N resulted in highest area-scaled (mean=2.45 kg N ha -1) and grain yield-scaled (mean=360 g N Mg -1) N 2O emissions. In contrast, CT+145 kg N had similar yield-scaled emissions as NT+202 and NT+145 kg N, and reduced area-scaled N 2O emissions by 65, 45, and 19% respectively, relative to CT+202 kg N, NT+202 kg N, and NT+145 kg N treatments. These preliminary results suggest that reducing pre-plant NH 3 rates by ~30% under CT has the potential to reduce N 2O emissions without significant yield declines in the CT phase of a NT-CT rotation, despite faster nitrification in CT.
  • Authors:
    • Mallarino, A. P.
    • Pagani, A.
  • Source: Agronomy Journal
  • Volume: 107
  • Issue: 1
  • Year: 2015
  • Summary: It is known that soil acidity can limit crop yield, but additional research is needed to identify more precisely optimum soil pH for corn ( Zea mays L.) and soybean [ Glycine max (L.) Merr.] and the within-field variation in yield response to liming. The objective of this study was to identify optimum soil pH for these crops by studying the variation of soil pH and grain yield response to liming within several Iowa fields. Fourteen 4-yr strip-trials were established in acidic Molisols from 2007 to 2009. The methodology used global positioning systems (GPS), dense soil sampling (0.12-0.18-ha cells), yield monitors, and geographical information systems (GIS). One-time treatments replicated two to five times were an unlimed control and limestone at 6.72 Mg ha -1 effective calcium carbonate equivalent (ECCE), incorporated into the soil in fields managed with tillage. Soil samples (15-cm depth) were collected before liming and annually after crop harvest. The lowest initial soil pH at each site ranged from 4.75 to 5.70. Maximum pH increase was reached 1 to 3 yr after liming. Grain yield response to lime varied greatly. Corn yield responded more frequently than soybean yield but the magnitude of the response did not differ consistently. Liming seldom increased yield with pH>6.0 in soils having a high subsoil pH (≥7.4) and CaCO 3 within a 1-m depth but often increased yield up to pH 6.5 with lower pH subsoil. The results provided improved criteria for site-specific soil pH and lime management.
  • Authors:
    • Prokopy,Linda Stalker
    • Carlton,J. Stuart
    • Arbuckle,J. Gordon, Jr.
    • Haigh,Tonya
    • Lemos,Maria Carmen
    • Mase,Amber Saylor
    • Babin,Nicholas
    • Dunn,Mike
    • Andresen,Jeff
    • Angel,Jim
    • Hart,Chad
    • Power,Rebecca
  • Source: Climatic Change
  • Volume: 130
  • Issue: 2
  • Year: 2015
  • Summary: The U.S. Cooperative Extension Service was created 100 years ago to serve as a boundary or interface organization between science generated at the nation's land grant universities and rural communities. Production agriculture in the US is becoming increasingly complex and challenging in the face of a rapidly changing climate and the need to balance growing crop productivity with environmental protection. Simultaneously, extension budgets are diminishing and extension personnel are stretched thin with numerous, diverse stakeholders and decreasing budgets. Evidence from surveys of farmers suggests that they are more likely to go to private retailers and consultants for information than extension. This paper explores the role that extension can play in facilitating climate change adaptation in agriculture using data from a survey of agricultural advisors in Indiana, Iowa, Michigan and Nebraska and a survey of extension educators in the 12 state North Central Region. Evidence from these surveys shows that a majority of extension educators believe that climate change is happening and that they should help farmers prepare. It also shows that private agricultural advisors trust extension as a source of information about climate change. This suggests that extension needs to continue to foster its relationship with private information providers because working through them will be the best way to ultimately reach farmers with climate change information. However extension educators must be better informed and trained about climate change; university specialists and researchers can play a critical role in this training process.
  • Authors:
    • Savabi, M. R.
    • Abdo, Z.
    • Sullivan, D. G.
    • Hubbard, R. K.
    • Scully, B. T.
    • Strickland, T. C.
    • Lee, R. D.
    • Olson, D. M.
    • Hawkins, G. L.
  • Source: Soil and Water Journal
  • Volume: 70
  • Issue: 3
  • Year: 2015
  • Summary: Although conservation tillage is widely believed to be an agricultural management practice effective for increasing soil carbon (C) accretion and associated soil quality, there is limited research to determine whether conservation tillage increases net C accretion versus simply altering the distribution of C content by soil depth. We implemented conservation farming practices (winter cover cropping plus strip tillage) for a nonirrigated corn (Zea mays L.) production system in the southeastern coastal plain of Georgia, United States, that had been previously managed under a conventional plow and harrow tillage regime. Total soil C and nitrogen (N) were measured on samples collected from 0 to 65 cm (0 to 25.6 in) at 57 sites before and after five years under conservation farming practices. Crop yield, winter and summer aboveground crop biomass production, and biomass C and N content were also measured annually at each site. Soil C increased an average of 20 Mg ha-1 (8.9 tn ac-1; 6 to 62 Mg C ha-1 [2.6 to 27.6 tn C ac-1], depending upon slope position) and was associated with a N increase of 2 Mg ha-1 (0.89 tn ac-1). Although 72% to 80% of the C accretion was in the top 35 cm (13.8 in), 3 to 6 Mg C ha-1 (1.3 to 2.6 tn C ac-1) was accreted from 35 to 65 cm (13.8 to 25.6 in). The soil C accreted during the study amounted to 36% of the net biomass C produced. Corn yield increased 2,200 kg ha-1 (1,964 lb ac-1) depending upon slope position (1,200 to 2,500 kg ha-1 [1,071 to 2,232 lb ac-1]) during the same time. Analysis indicated that soil C content from 15 to 35 cm (5.9 to 13.8 in) was the soil parameter primarily associated with corn yield. Season rainfall from planting to corn silking stage for both corn production years was the lowest in the past 45 years (20 to 25 cm [7.8 to 9.8 in] below the net crop demand) suggesting that soil C-mediated increase in plant-available soil water was a mechanism contributing to improved corn yield. Calculated estimates (from soil clay, sand, and C content) of increased soil water holding capacity suggest that C accretion in the top 35 cm (13.8 in) of soil potentially increased water storage enough to supply up to four days' worth of additional crop water demand. These results indicated that conservation farming practices can increase soil C and N accretion in degraded sandy soils of the humid southeastern United States coastal plain, and that increased soil C may potentially mitigate the deleterious effects of short-term rainfall deficits in nonirrigated production systems.
  • Authors:
    • Huang, S.
    • Pan, X.
    • Shi, Q.
    • Zeng, Y.
    • Sun, Y.
  • Source: Article
  • Volume: 153
  • Year: 2015
  • Summary: Runoff from farmland is of great importance to both agricultural and environmental sustainability. In the present study, a meta-analysis was conducted to quantify the effectiveness of no-tillage (NT) in reducing surface runoff and to explore the factors controlling the effectiveness. Results showed that overall, NT significantly reduced runoff by 21.9% and 27.2% compared to reduced tillage (RT) and conventional moldboard plow (MP), respectively. The effectiveness of NT in reducing runoff was higher under simulated than natural rainfall, particularly as compared to MP. The reduction in runoff under NT was significant and greatest for moderate slope gradients (5-10%) relative to both RT and MP, but without statistical significance for both gentle (10%) slope gradients. As compared to MP, the effectiveness of NT in reducing runoff decreased over time, whereas no such trend was found relative to RT. Compared to RT, NT significantly reduced runoff in soils with low clay content (<33% clay), while resulting in a slight but non-significant increase in runoff in soils with high clay content (=33% clay). The effectiveness of NT in reducing runoff compared to RT did not vary with tillage direction. Runoff was significantly reduced by NT with crop residue retention relative to RT, but not with residue removal. Our results conclude that NT needs to be adapted to specific environmental conditions and management practices for improved controls on runoff. © 2015.
  • Authors:
    • Helmers, M. J.
    • Kostel, J. A.
    • James, D. E.
    • Boomer, K. M. B.
    • Porter, S. A.
    • Tomer, M. D.
    • Isenhart, T. M.
    • McLellan, E.
  • Source: Agronomy Journal
  • Volume: 44
  • Issue: 3
  • Year: 2015
  • Summary: Spatial data on soils, land use, and topography, combined with knowledge of conservation effectiveness, can be used to identify alternatives to reduce nutrient discharge from small (hydrologic unit code [HUC]12) watersheds. Databases comprising soil attributes, agricultural land use, and light detection and ranging-derived elevation models were developed for two glaciated midwestern HUC12 watersheds: Iowa's Beaver Creek watershed has an older dissected landscape, and Lime Creek in Illinois is young and less dissected. Subsurface drainage is common in both watersheds. We identified locations for conservation practices, including in-field practices (grassed waterways), edge-of-field practices (nutrient-removal wetlands, saturated buffers), and drainage-water management, by applying terrain analyses, geographic criteria, and cross-classifications to field- and watershed-scale geographic data. Cover crops were randomly distributed to fields without geographic prioritization. A set of alternative planning scenarios was developed to represent a variety of extents of implementation among these practices. The scenarios were assessed for nutrient reduction potential using a spreadsheet approach to calculate the average nutrient-removal efficiency required among the practices included in each scenario to achieve a 40% NO 3-N reduction. Results were evaluated in the context of the Iowa Nutrient Reduction Strategy, which reviewed nutrient-removal efficiencies of practices and established the 40% NO 3-N reduction as Iowa's target for Gulf of Mexico hypoxia mitigation by agriculture. In both test watersheds, planning scenarios that could potentially achieve the targeted NO 3-N reduction but remove <5% of cropland from production were identified. Cover crops and nutrient removal wetlands were common to these scenarios. This approach provides an interim technology to assist local watershed planning and could provide planning scenarios to evaluate using watershed simulation models. A set of ArcGIS tools is being released to enable transfer of this mapping technology.